Luteinizing Hormone Levels Are Positively Correlated with Plasma Amyloid-β Protein Levels in Elderly Men

Article type: Research Article

Authors: Verdile, Giuseppe^{a; b; c; d} | Yeap, Bu B.^{e; f} | Clarnette, Roger M.^{b; c; g} | Dhaliwal, Satvinder^h | Burkhardt, Melanie S.^{b; c; i} | Chubb, S.A Paul^j | De Ruyck, Karl^{b; c} | Rodrigues, Mark^{b; c} | Mehta, Pankaj D.^k | Foster, Jonathan K.^{a; b; c} | Bruce, David G.^{e; g} | Martins, Ralph N.^{a; b; c; d; *}

Affiliations: [a] Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA 6027, Australia | [b] Sir James McCusker Alzheimer's Disease Research Unit, Hollywood Private Hospital, Nedlands, WA, Australia, 6009 | [c] School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA 6027, Australia | [d] School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, WA 6009, Australia | [e] School of Medicine and Pharmacology, University of Western Australia, Crawley, WA 6009, Australia | [f] Department of Endocrinology and Diabetes, Fremantle Hospital, Fremantle, WA 6959, Australia | [g] Department of Geriatric Medicine, Fremantle Hospital, Fremantle, WA 6959, Australia | [h] School of Public Health, Curtin University, Bentley, WA 6102, Australia | [i] School of Psychology, Murdoch University, Murdoch, WA 6150, Australia | [j] Department of Biochemistry, Fremantle Hospital, Fremantle, WA 6959, Australia | [k] Department of Immunology, Institute for Basic Research in Developmental Disabilities, Forest Hill Road, Staten Island, NY 10314-6399, USA

Correspondence: [*] Corresponding author: Prof. Ralph Martins, Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA 6027, Australia. Tel.: +61 8 6304 5456; Fax: +61 8 6304 5851; E-mail: [email protected]

Abstract: Dysregulation of the hypothalamic pituitary gonadal (HPG) axis during aging has been associated with increased risk of cognitive decline and developing dementia. Compared to controls, men with Alzheimer's disease (AD) have been shown to have lower serum testosterone levels and higher serum luteinizing hormone (LH) levels. As serum free testosterone concentration is negatively correlated with LH in older men, the independent contributions of these hormones to the pathogenesis of AD warrants further clarification. To explore this notion, we measured plasma amyloid-β (Aβ), serum testosterone, serum LH and other biochemical parameters in 40 cognitively normal elderly men. Multiple linear regression analysis revealed that serum LH concentration is the only parameter that significantly correlates with plasma Aβ levels in these men (r=0.5, p=0.041). These results suggest that increased serum LH concentration, rather than lower serum free testosterone, is associated with the accumulation of Aβ in plasma. Larger, longitudinal human studies are needed to determine the significance of LH in the pathogenesis of AD.

Keywords: Alzheimer's disease, amyloid-β, cognition, luteinizing hormone, testosterone

DOI: 10.3233/JAD-2008-14208

Journal: Journal of Alzheimer's Disease, vol. 14, no. 2, pp. 201-208, 2008